Minimizing interference between communication networks

ABSTRACT

Methods, systems, and devices are described for minimizing mutual interference between networks that implement different protocols. In one embodiment, a first network device of a first network may exchange coexistence information with a second network device of a second network to determine whether to share resources or reduce transmit power based, at least in part, on the interference detected at the first network device from a transmission of the second network device. In one embodiment, both the first and the second network devices may independently and iteratively reduce their respective transmit power to minimize interference between the interfering networks. The first network device may reduce its transmit power based on an interference of the second network device and vice versa. In another embodiment, the network device with a lower priority may minimize its transmit power to reduce interference with the network device with a higher priority.

RELATED APPLICATIONS

This application is a Continuation of and claims the priority benefit ofU.S. application Ser. No. 14/305,964 filed on Jun. 16, 2014.

BACKGROUND

Embodiments of this disclosure generally relate to the field ofcommunication networks and, more particularly, to minimizinginterference between communication networks.

A powerline communication (PLC) network and a digital subscriber line(DSL) network typically operate on an overlapping set of operatingfrequencies within the 2-88 MHz frequency band. PLC devices in the PLCnetwork exchange communications via power lines. DSL devices in the DSLnetwork exchange communications via telephone lines. Although the PLCdevices and the DSL devices use different communication media fortransmission, the PLC transmissions may electromagnetically couple withthe DSL transmissions and vice versa. This may cause interference in thePLC network and the DSL network.

SUMMARY

Various embodiments for minimizing interference between communicationnetworks are disclosed. In one embodiment, a first network device of afirst communication network determines an interference level associatedwith a second network device of a second communication network;determines, in response to determining that the interference level doesnot exceed an interference threshold, to reduce at least one memberselected from the group consisting of: a first transmit power of thefirst network device, and a second transmit power of the second networkdevice; and determines to share a communication resource between thefirst network device and the second network device in response todetermining that the interference level exceeds the interferencethreshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments may be better understood, and numerous objects,features, and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1 is a block diagram illustrating an example mechanism forminimizing interference between communication networks;

FIG. 2 is an example conceptual diagram illustrating proximatecommunication networks that are communicatively coupled via an alternatecommunication network for coordinated interference mitigation;

FIG. 3 is a flow diagram illustrating example operations for activecoordination to minimize interference between communication networks;

FIG. 4 is a flow diagram illustrating example operations for activecoordination to determine how to minimize interference betweencommunication networks;

FIG. 5 is a flow diagram illustrating example operations of a symmetrictechnique for minimizing interference between communication networks;

FIG. 6 is a flow diagram illustrating example operations of anasymmetric technique for minimizing interference between communicationnetworks; and

FIG. 7 is a block diagram of one embodiment of an electronic deviceincluding a mechanism for minimizing interference between communicationnetworks.

DESCRIPTION OF EMBODIMENT(S)

The description that follows includes exemplary systems, methods,techniques, instruction sequences, and computer program products thatembody techniques of this disclosure. However, it is understood that thedescribed embodiments may be practiced without these specific details.For instance, although examples refer to minimizing interference betweena powerline communication (PLC) network and a very-high-bit-rate digitalsubscriber line (VDSL) network, embodiments are not so limited. In otherembodiments, the techniques described herein may be implemented tominimize interference between other suitable communication networks thatshare at least a portion of their respective operating frequency band.In other instances, well-known instruction instances, protocols,structures, and techniques have not been shown in detail in order not toobfuscate the description.

A PLC network and a VDSL network typically operate on an overlapping setof operating frequencies of different communication media. However, ifthe PLC network and the VDSL network are in close proximity to eachother, PLC transmissions may become electromagnetically coupled withVDSL transmissions, and vice versa. Consequently, the PLC network mayexperience interference from transmissions of the VDSL network and viceversa. Increasing a maximum transmit power (e.g., determined by powerregulatory groups) associated with the PLC network can enhance theperformance of the PLC network. However, increasing the maximum transmitpower of the PLC network may increase the interference in the VDSLnetwork and may further degrade the performance of the VDSL network.

A PLC device and/or a VDSL device may implement functionality toestimate and minimize interference between the devices. In someembodiments, the PLC device and the VDSL device may exchange coexistencemessages via an alternate communication network (e.g., Ethernet) todetermine how to minimize mutual interference. For example, the PLCdevice and the VDSL device may exchange coexistence messages todetermine whether to share communication resources (e.g., time on thewire, frequency spectrum, etc.) or reduce the transmit power dependingon the interference between the PLC network and the VDSL network. Thistechnique may be referred to as “coordinated interference reductiontechnique” and will be further described in FIGS. 1-4. In anotherembodiment, both the PLC device and the VDSL device may iterativelyreduce their respective transmit power to minimize interference betweenthe PLC and the VDSL devices. In this embodiment, the PLC device mayestimate a transmit power reduction factor based on the interferenceassociated with a VDSL transmission. Likewise, the VDSL device may alsoestimate a transmit power reduction factor based on the interferenceassociated with a PLC transmission. Each device can then reduce itstransmit power by the appropriate transmit power reduction factor. Thistechnique may be referred to as “symmetric interference reductiontechnique” and will be further described in FIGS. 1 and 5. In anotherembodiment, functionality for estimating the interference and reducingthe transmit power may be implemented on either the PLC device or theVDSL device. This technique may be referred to as “asymmetricinterference reduction technique” and will be further described in FIGS.1 and 6. The mechanisms described below can help minimize mutualinterference between proximate communication networks. The networkdevices of at least one of the proximate communication networks maytransmit at a determined transmit power to minimize interference withthe other communication network without causing performance degradationwithin its communication network.

FIG. 1 is a block diagram illustrating an example mechanism forminimizing interference between communication networks. FIG. 1 depictscommunication networks 100 and 110. The communication network 100includes a network device 102; while the communication network 110includes a network device 112. The network device 102 includes aninterference detection module 104, a transmit power estimation module106, and a coexistence module 108. Similarly, the network device 112includes an interference detection module 114, a transmit powerestimation module 116, and a coexistence module 118. The coexistencemodules 108 and 118 are depicted using dashed lines to indicate thatthey are optional, i.e., the network devices 102 and 112 may or may notinclude the coexistence module (e.g., coexistence functionality)depending on the implementation, as will be described further below.Additionally, depending on the implementation, the communication network100 may or may not be communicatively coupled with the communicationnetwork 110 via an alternate communication network (depicted using adashed line). Although not depicted in FIG. 1, the communicationnetworks 100 and 110 may each include multiple network devices. Also,multiple network devices in each communication network may include aninterference detection module, a transmit power estimation module,and/or a coexistence module similarly as depicted for the networkdevices 102 and 112.

In some embodiments, the communication network 100 may be a PLC network.For example, the communication network 100 may implement HomePlug®AV/AV2/GreenPHY protocols, G.hn protocols, or other suitable protocolsthat use a powerline medium for communication. In one embodiment, thenetwork device 102 may be any suitable electronic device, such as adedicated PLC device, a desktop computer, a laptop computer, a tabletcomputer, a television set-top box, a gaming console, and a smartappliance that includes hardware, software, and/or firmware to implementPLC protocols for communication. For example, a dedicated PLC device maybe a PLC modem. In some embodiments, the communication network 110 maybe a VDSL network. For example, the communication network 110 mayimplement G.fast protocols or other suitable protocols that usetelephone lines for communication. In some embodiments, the networkdevice 112 may be any suitable electronic device, such as a dedicatedVDSL device or another electronic device that includes hardware,software, and/or firmware to implement VDSL protocols for communication.For example, a dedicated VDSL device may be a VDSL modem.

In one embodiment, the network devices 102 and 112 can activelycoordinate with each other via an alternate communication network todetermine how to minimize interference. This technique may be referredto as a “coordinated interference reduction technique.” In thisembodiment, network devices in the interfering communication networks100 and 110 may exchange coexistence messages to determine how tominimize interference between the communication networks 100 and 110.The interference between two communications networks is also referred toas “mutual interference.” FIG. 2 is an example conceptual diagram of aPLC network 200 communicatively coupled with a VDSL network 210 viaEthernet 212 for coexistence using the coordinated interferencereduction technique. The PLC network 200 includes PLC devices 202 and204; while the VDSL network 210 includes VDSL devices 206 and 208. Inthe example of FIG. 2, the PLC device 204 is communicatively coupledwith the VDSL device 208 of the VDSL network 210 via the Ethernet 212.The PLC device 204 and the VDSL device 208 may use the Ethernet tomanage coexistence of the two technologies. In some embodiments, asdepicted in FIG. 2, one PLC device 204 (e.g., a network device includinga PLC modem) and one VDSL device 208 (e.g., a network device including aVDSL modem) may be coupled with each other via Ethernet 212. The PLCdevice 204 and the VDSL device 208 may exchange coexistence messages onbehalf of other PLC devices and other VDSL devices, respectively, tominimize interference between the networks 200 and 210. In otherembodiments, some or all of the PLC devices of the PLC network 200 maybe coupled with some/all of the VDSL devices of the VDSL network 210. Inthis embodiment, some/all of the PLC devices may directly exchangecoexistence messages with some/all of the interfering VDSL devices (andvice versa) to reduce mutual interference. Although FIG. 2 describesusing Ethernet to communicatively couple the PLC network 200 and theVDSL network 210 for the coordinated interference reduction technique,embodiments are not so limited. In other embodiments, other suitablewired or wireless communication networks may be used to communicativelycouple the PLC network 200 and the VDSL network 210. For example, thePLC device 204 and the VDSL device 208 may use a wireless local areanetwork (WLAN) communication protocol, such as an IEEE 802.11communication protocol, a multimedia over coax alliance (MoCA)communication protocol, or another suitable communication protocol toimplement the coordinated interference reduction technique. In otherembodiments, the PLC device 204 and the VDSL device 208 may use PLCprotocols or VDSL communication protocols to implement the coordinatedinterference reduction technique.

Referring back to FIG. 1, for the coordinated interference reductiontechnique, the coexistence modules 108 and 118 may exchange coexistencemessages via the Ethernet to determine whether to share resources orreduce their transmit power. The coexistence modules 108 and 118 maydetermine whether to share resources or reduce the transmit powerdepending on the interference (also referred to as “interference level”)between the communication networks 100 and 110. Sharing resources mayinclude sharing transmission time on the communication medium, sharingfrequency channels (or frequency bands) of a frequency spectrum, etc. Ifthe interference between the network devices 102 and 112 is low, thenetwork device 102 and/or the network device 112 may reduce theirrespective transmit power to minimize the interference. For example, thenetwork devices 102 and/or 112 may reduce the transmit power if theinterference lies below an interference threshold. In oneimplementation, the interference threshold may be predefined at thenetwork devices 102 and 112. In another implementation, the interferencethreshold may be dynamically determined by the network devices 102and/or 112. As another example, the network devices 102 and/or 112 mayreduce the transmit power if the interference exceeds a lowerinterference threshold but does not exceed an upper interferencethreshold. In one embodiment, the coexistence modules 108 and 118 mayexchange coexistence messages to negotiate a transmit power reductionfactor to decrease the transmit power. In another embodiment, thetransmit power estimation module 106 may estimate the transmit powerreduction factor for the network device 112. The coexistence module 108may notify the coexistence module 118 to reduce the transmit power ofthe network device 112 by the transmit power reduction factor determinedby the network device 102. In another embodiment, the transmit powerestimation module 116 may estimate the transmit power reduction factorfor the network device 102. The coexistence module 118 may notify thecoexistence module 108 to reduce the transmit power of the networkdevice 102 by the transmit power reduction factor determined by thenetwork device 112.

If the interference between the network devices 102 and 112 is high, thecoexistence modules 108 and 118 may exchange coexistence messages todetermine how to share communication resources. For example, the networkdevices 102 and 112 may determine to share the communication resourcesif the interference determined by the interference detection module 104and/or 114 exceeds the interference threshold. As another example, thenetwork devices 102 and 112 may determine to share the communicationresources if the interference exceeds both the lower interferencethreshold and the upper interference threshold. Alternatively, thenetwork devices 102 and 112 may determine to share the communicationresources if reducing the transmit power at the network device 102(and/or the network device 112) will cause performance degradation inthe communication network 100 (and/or the communication network 110).The coexistence modules 108 and 118 may exchange coexistence messagesvia the alternate communication network to determine whether the networkdevices 102 and 112 should share the communication resources in time orin frequency. To share the communication resources in time, each networkdevice may transmit messages during an assigned communication time slot.To share the communication resources in frequency, each network devicemay transmit messages on a set of assigned frequency channels (orfrequency sub-bands). Operations for the coordinated interferencereduction technique will be further described in FIGS. 3-4.

In another embodiment, network devices from both the interferingcommunication networks 100 and 110 may each execute operations todetermine the interference and reduce their respective transmit power.This technique may be referred to as a symmetric interference reductiontechnique.” The interference detection module 104 may detect a preambleof a transmission initiated by the network device 112. The interferencedetection module 104 may determine the interference caused by thenetwork device 112 (at the network device 102) based on the signalstrength of the detected preamble. The transmit power estimation module106 may determine by how much to reduce the transmit power (“transmitpower reduction factor”) of the network device 102 based on theinterference associated with the network device 112. Likewise, for thenetwork device 112, the interference detection module 114 may detect apreamble of a transmission initiated by the network device 102. Theinterference detection module 114 may determine the interference causedby the network device 102 (at the network device 112) based on thesignal strength of the detected preamble. The transmit power estimationmodule 116 may determine a transmit power reduction factor of thenetwork device 112 based on the interference associated with the networkdevice 102. The network devices 102 and 112 may reduce their respectivetransmit power by the determined transmit power reduction factor. Thenetwork devices 102 and 112 can iteratively reduce their respectivetransmit power to minimize interference between the proximatecommunication networks 100 and 110. Operations for the symmetricinterference reduction technique will be further described in FIG. 5.

In another embodiment, either the network device 102 or the networkdevice 112 may execute operations to determine the interference andminimize the transmit power. This technique may be referred to as anasymmetric interference reduction technique.” In other words, a networkdevice from one of the interfering communication networks 100 and 110may reduce its transmit power to minimize interference to the othercommunication network. In one implementation, the network device with alower priority (e.g., the network device 102) may estimate theinterference generated by the network device with the higher priority(e.g., the network device 112). The interference detection module 104may estimate the attenuation (also referred to as “attenuation level”)between the network devices 102 and 112 in response to detectingtransmissions from the network device 112. The transmit power estimationmodule 106 may determine the transmit power reduction factor assumingattenuation symmetry and based on knowledge of the minimum power thatcan be detected by the network device 112 and the attenuation betweenthe network devices 102 and 112. The network device with the lowerpriority may then reduce its transmit power to minimize interference tothe network device with the higher priority. In one example, the PLCdevice may have a lower priority as compared to the VDSL device. In thisexample, the PLC device may detect a VDSL transmission and reduce itstransmit power to minimize interference with the VDSL device. In thisexample, the VDSL device may not reduce its transmit power or try tominimize interference caused to the PLC device. However, in anotherexample, the VDSL device may detect a PLC transmission and reduce itstransmit power to minimize interference with the PLC device. In thisexample, the PLC device may not reduce its transmit power or try tominimize interference caused to the VDSL device. Operations for theasymmetric interference reduction technique will be further described inFIG. 6.

FIG. 3 is a flow diagram (“flow”) 300 illustrating example operationsfor active coordination to minimize interference between communicationnetworks. The flow 300 begins at block 302.

At block 302, a first network device of a first communication networkdetects a transmission associated with a second network device of asecond communication network. Referring to FIG. 1, the interferencedetection module 104 of the network device 102 may detect a transmissioninitiated by the network device 112. In one example, a PLC device maydetect a transmission initiated by a VDSL device in a proximate VDSLnetwork. In another example, the VDSL device may detect a transmissioninitiated by a PLC device in a proximate PLC network. Various techniquesmay be employed to detect a transmission associated with the secondnetwork device. In one embodiment, the first network device mayimplement a preamble detection mechanism to detect the preamble of thetransmission associated with the second network device. In anotherembodiment, the first network device may identify a transmission bydetecting an increase in the signal strength detected at the firstnetwork device. The flow continues at block 304.

At block 304, the first network device estimates an interferenceassociated with the second network device. For example, the interferencedetection module 104 may estimate the interference associated with thenetwork device 112 based, at least in part, on the transmissiongenerated by the network device 112. In some embodiments, the firstnetwork device may estimate the interference associated with the secondnetwork device based, at least in part, on the signal strength of thepreamble of the second network device. In another embodiment, the firstnetwork device may determine the interference associated with the secondnetwork device based, at least in part, on an estimated attenuationbetween the first network device and the second network device. In someembodiments, the first network device may determine multipleinterference measurements over a time interval. The first network devicemay determine an average interference measurement by combining themultiple interference measurements. As will be further described below,the first network device may use the interference to determine whetherto reduce its transmit power or share communication resources with thesecond network device. Using the average interference measurement canhelp minimize the effects of background noise and transmissions fromother devices (e.g., that do not belong to the second communicationnetwork) on the estimate of the interference associated with the secondnetwork device. The flow continues at block 306.

At block 306, the first network device provides a coexistence message tothe second network device via an alternate communication network todetermine whether to reduce the transmit power or share resources withthe second network device based, at least in part, on the interference.For example, the coexistence module 108 may exchange coexistencemessages with the coexistence module 118 to determine how to minimizeinterference between the communication networks 100 and 110. Theinterference between the communication networks 100 and 110 may also bereferred to as “mutual interference.” In one implementation, as shown inFIG. 2, the PLC network 200 may be coupled with the VDSL network 210 viathe Ethernet 212. In this example, the PLC device 204 and the VDSLdevice 208 can actively coordinate with each other via the Ethernet 212to determine how to minimize mutual interference. The PLC device 204 andthe VDSL device 208 may exchange Ethernet coexistence messages via theEthernet 212 to determine whether and by how much to reduce the transmitpower, whether and how to share communication resources, whether thedetected interference has decreased, etc.

The first network device may determine the interference based on adetected transmission of the second network device. In one embodiment,the first network device may use two interference thresholds todetermine how to minimize the interference—a lower interferencethreshold and an upper interference threshold. If the interference doesnot exceed the lower interference threshold, the first network devicemay determine not to reduce the transmit power and not to shareresources (e.g., not take any action). If the interference exceeds thelower interference threshold but does not exceed the upper interferencethreshold, the first network device may determine that mutualinterference can be minimized by reducing the transmit power. If theinterference exceeds the upper interference threshold, the first networkdevice may determine that mutual interference cannot be minimized bysimply reducing the transmit power. In this case, the first networkdevice may determine to share communication resources with the secondnetwork device. In another embodiment, the first network device may useone interference threshold to determine how to minimize theinterference. If the interference exceeds the interference threshold,the first network device may determine that mutual interference can beminimized by reducing the transmit power. If the interference exceedsthe interference threshold, the first network device may determine toshare communication resources with the second network device.

If the first network device determines to reduce its transmit power, thefirst network device can exchange coexistence messages with the secondnetwork device to determine a transmit power reduction factor. The firstnetwork device may reduce its transmit power by the transmit powerreduction factor and may initiate subsequent transmissions using thereduced transmit power. In some embodiments, the first network devicemay also transmit a coexistence message to the second network device toindicate by how much the second network device should reduce itstransmit power. In some embodiments, after determining the transmitpower reduction factor, the first network device may determine whetherreducing the transmit power will degrade the performance of the firstcommunication network. In another embodiment, the first network devicemay receive a coexistence message from the second network deviceindicating whether reducing the transmit power of the second networkdevice will degrade the performance of the second communication network.The network devices 102 and 112 may determine to share communicationresources if reducing the transmit power will degrade the performance ofthe first and/or the second communication networks. If the first networkdevice determines to share the communication resources, the firstnetwork device may exchange coexistence messages with the second networkdevice to determine how to share the communication resources. Forexample, the coexistence modules 108 and 118 may exchange coexistencemessages to allocate unique communication time slots and/or uniquecommunication frequency channels to the network devices 102 and 112 aswill be further described in FIG. 4. From block 306, the flow ends.

FIG. 4 is a flow diagram 400 illustrating example operations for activecoordination to determine how to minimize interference betweencommunication networks. The flow 400 begins at block 402.

At block 402, a first network device of a first communication networkestimates the interference associated with a second network device of asecond communication network. Referring to the example of FIG. 1, theinterference detection module 104 may determine the interference causedby the network device 112 at the network device 102. In one example, aPLC device of a PLC network may estimate the interference associatedwith a VDSL device of a proximate VDSL network. As another example, theVDSL device may estimate the interference associated with the PLCdevice. In some embodiments, the first network device may coordinatewith the second network device to measure the interference attributableto the second network device. The first network device and the secondnetwork device may exchange coexistence messages to determine whichnetwork device should transmit during a time interval and which networkdevice should detect the interference. For example, based on exchangingcoexistence messages, the PLC device may determine to transmit during afirst time interval. During the first time interval, the VDSL device maylisten for transmissions from the PLC device and measure theinterference associated with the PLC device. To determine theinterference, the VDSL device may notify all other VDSL devices in theVDSL network to temporarily defer transmissions during the first timeinterval. This can ensure that transmissions detected during the firsttime interval were generated by PLC devices in the PLC network. The VDSLdevice may estimate the interference based on the transmissions of thePLC device that were detected during the first time interval. Likewise,the VDSL device may transmit during a second time interval; while thePLC device may determine the interference associated with the VDSLdevice based on PLC transmissions received during the second timeinterval. To determine the interference, the PLC device may notify allother PLC devices in the PLC network to temporarily defer transmissionsduring the second time interval. This can ensure that transmissionsdetected during the second time interval were generated by VDSL devicesin the VDSL network.

Additionally, in some embodiments, the first network device and thesecond network device may also coordinate to select a quiet timeinterval for measuring the background noise. None of the network devicesin the first communication network and the second communication networkmay transmit any messages during the quiet time interval. Accordingly,the noise measured during the quiet time interval may not be associatedwith either the first communication network or the second communicationnetwork. Instead, the noise measured during the quiet time interval mayinclude environmental noise, noise on the powerline medium caused byelectronic devices connected to the power lines, etc.

The first network device (e.g., the PLC device or the VDSL device) mayimplement various techniques to determine the interference associatedwith the second network device. For example, the first network devicemay detect a preamble of the transmission received at the first networkdevice from the second network device. The preamble is typicallytransmitted using a robust transmission scheme and may include shortrepeated orthogonal frequency division multiplexing (OFDM) symbols. Thefirst network device may correlate a received signal and a predefinedsignal to determine whether the received signal includes the preamble ofthe second network device. If there is a peak in the correlation result,this can indicate that the received signal includes the preamble of thesecond network device (e.g., that the received signal was generated bythe second network device). For preamble detection, the first networkdevice may have a priori knowledge of the characteristics of the secondnetwork device such as, symbol duration, phase of the transmission, etc.

The first network device may determine the interference based, at leastin part, on the signal strength of the detected preamble. For example,the first network device may determine the interference associated withthe second network device using the received signal strength indicator(RSSI) measurement of the detected preamble, automatic gain control(AGC) settings of the first network device, or another suitable signalstrength measurement. In one embodiment, the first network device maysubtract a power detection threshold and the background noise from thesignal strength to yield the interference associated with the secondnetwork device. The power detection threshold may represent the minimumsignal strength that may be detected by the first network device. Thepower detection threshold may depend on the receiver sensitivity, noisein the first communication network, and other such factors. For example,the first network device may detect a −80 dB signal from the secondnetwork device. If the power detection threshold of the first networkdevice is −140 dB, the interference may be −60 dB (e.g., −140 dB-−80dB). After determining the interference associated with the secondnetwork device, the flow continues at block 404.

At block 404, the first network device determines whether theinterference exceeds an interference threshold. For example, theinterference detection module 104 may determine whether the interferenceassociated with the second network device exceeds the interferencethreshold. The interference threshold may be determined based on themaximum amount of interference that can be tolerated at the firstnetwork device, the power detection threshold of the first networkdevice, the background noise of the first communication network, and/orother suitable factors. In some embodiments, the first network devicemay use two interference thresholds to determine whether to reduce thetransmit power or share resources with the second network device. If theinterference exceeds a lower interference threshold but does not exceedan upper interference threshold, the first network device may determineto reduce the transmit power and the flow continues at block 406. If theinterference exceeds both the lower and the upper interferencethresholds, the first network device may determine to sharecommunication resources with the second network device and the flowcontinues at block 414. Although not depicted in FIG. 4, if theinterference does not exceed the first interference threshold, the firstnetwork device may determine not to take any action (e.g., not to reducethe transmit power and not to share resources with the second networkdevice). The first network device may transmit a coexistence message tothe second network device indicating that the interference is below thefirst interference threshold. The first network device may continue tomonitor the interference generated by the second network device. Inanother embodiment, the first network device may use a singleinterference threshold to determine whether to reduce the transmit poweror share resources with the second network device. If the interferencedoes not exceed the interference threshold, the first network device maydetermine to reduce the transmit power and the flow continues at block406. If the interference exceeds the interference threshold, the firstnetwork device may determine to share communication resources with thesecond network device and the flow continues at block 414.

At block 406, a transmit power reduction factor is estimated forreducing the transmit power of the first network device and/or thesecond network device. For example, the transmit power estimation module106 may estimate the transmit power reduction factor for the firstnetwork device and/or the second network device to minimize theinterference. In one embodiment, the coexistence module 108 may exchangecoexistence messages with the coexistence module 118 to determinewhether one or both of the network devices should reduce theirrespective transmit power. In one embodiment, the first network deviceand the second network device may negotiate with each other and agree ona single transmit power reduction factor for decreasing the transmitpower. In this embodiment, the first network device and the secondnetwork device may each determine to reduce their respective transmitpower by the same transmit power reduction factor. For example, thetransmit power reduction factor for the first network device may be halfthe amount of the interference associated with the second networkdevice. In this example, if the first network device detects aninterference of −15 dB, the first and the second network devices mayeach reduce their transmit power by −7.5 dB, resulting in an overalltransmit power reduction of −15 dB and effectively zero interference. Inanother embodiment, the first network device and the second networkdevice may exchange coexistence messages and determine a differenttransmit power reduction factor for decreasing the transmit power of thefirst network device and the second network device. For example, thetransmit power reduction factor for the first network device may be anysuitable percentage of the amount of the interference associated withthe second network device. In another embodiment, the first networkdevice may determine the transmit power reduction factor for reducingthe transmit power of the second network device based, at least in part,on the interference associated with the second network device.

In another embodiment, the first network device may receive acoexistence message from the second network device that indicates theamount by which the first network device should reduce its transmitpower. In another embodiment, the first network device may receive acoexistence message from the second network device indicating theinterference associated with the first network device that was detectedat the second network device. The first network device may determine thetransmit power reduction factor for reducing its transmit power based,at least in part, on the amount of interference detected by the secondnetwork device and caused by the first network device. For example, thetransmit power reduction factor for the first network device may be halfthe amount of the interference associated with the first network device.As another example, the transmit power reduction factor for the firstnetwork device may be any suitable percentage of the amount of theinterference associated with the first network device. In anotherembodiment, the first network device may exchange coexistence messageswith the second network device to select a predefined transmit powerreduction factor. The first network device may reduce its transmit powerby the predefined transmit power factor irrespective of the interferenceassociated with the second network device or the interference associatedwith the first network device. In another embodiment, the first networkdevice may exchange coexistence messages with the second network deviceto select multiple predefined transmit power reduction factors formultiple interference ranges. For example, if the interferenceassociated with the second network device falls within a firstinterference range, the first network device may select a firstpredefined transmit power reduction factor. If the interference fallswithin a second interference range, the first network device may selecta second predefined transmit power reduction factor, and so on. Inanother embodiment, the first network device may receive a coexistencemessage from the second network indicating the power detection thresholdor detection sensitivity of the second network device. The first networkdevice may select the transmit power reduction factor so that theinterference generated by the first network device at the second networkdevice is below the power detection threshold of the second networkdevice. In another embodiment, the first network device may receive acoexistence message from the second network indicating the interferencethreshold of the second network device. The first network device mayselect the transmit power reduction factor so that the interferencegenerated by the first network device at the second network device isbelow the interference threshold of the second network device. The flowcontinues at block 408.

At block 408, the first network device exchanges coexistence messageswith the second network device, via an alternate communication network,to reduce the transmit power by the transmit power reduction factor. Inone embodiment, the PLC device may exchange coexistence messages withthe VDSL device via an Ethernet to reduce the transmit power of the PLCdevice and/or the VDSL device. Referring to FIG. 1, the coexistencemodule 108 may exchange coexistence messages with the coexistence module118 via the alternate communication network. In one example, asdescribed above, the first network device and the second network devicemay exchange coexistence messages and determine a transmit powerreduction factor for decreasing the transmit power of the first networkdevice and/or the second network device. As another example, the firstnetwork device may notify the second network device via the Ethernet toreduce its transmit power by a transmit power reduction factordetermined based on the amount of interference associated with thesecond network device. The first network device may also determine toreduce its transmit power by the same or a different transmit powerreduction factor. In another example, the first network device mayreceive a notification from the second network device indicating thetransmit power reduction factor for reducing the transmit power of thefirst network device. In some embodiments, the first network device maynotify the second network device to reduce the transmit power and maydetermine not to reduce its transmit power based on a message receivedfrom the second network device. For example, the PLC device may detectinterference from the VDSL network but the VDSL device may not detectinterference from the PLC network. In this example, the PLC device maynotify the VDSL device to reduce its transmit power. However, the PLCdevice may receive a message from the VDSL device indicating that thePLC device should not reduce its transmit power. The flow continues atblock 410.

At block 410, the first network device determines whether the reducedtransmit power will cause performance degradation in the first or secondcommunication networks. For example, the transmit power estimationmodule 106 may simulate or estimate the effect of reducing the transmitpower of the network device 102 by the transmit power reduction factor.As another example, the coexistence module 108 may receive a coexistencemessage from the coexistence module 118. The coexistence message mayindicate that reducing the transmit power will degrade the performanceof the second communication network 110. If reducing the transmit powerwill cause performance degradation in either the first or the secondcommunication networks, the flow continues at block 414. Otherwise, theflow continues at block 412.

At block 412, the first network device reduces the transmit power by thetransmit power reduction factor. The first network device may initiatesubsequent transmissions in the first communication network using thereduced transmit power. In some embodiments, the first network devicemay receive a coexistence message indicating that the transmit power ofthe second network device was reduced by the transmit power reductionfactor. From block 412, the flow ends. Although FIG. 4 depicts the flowending after block 412, embodiments are not so limited. In otherembodiments, the first network device may continue to monitor theinterference associated with the second network device (e.g., the flow400 may move from block 412 to block 402).

At block 414, the first network device exchanges coexistence messageswith the second network device via the alternate communication networkto determine how to share communication resources between the firstnetwork device and the second network device. For example, thecoexistence module 108 may exchange coexistence messages with thecoexistence module 118 to determine how to share the communicationresources. In one embodiment, if the first network device uses oneinterference threshold to determine how to minimize the interference,the first network device may determine to share the communicationresources with the second network device if the interference associatedwith the second network device exceeds the interference threshold. Inanother embodiment, if the first network device uses two interferencethresholds to determine how to minimize the interference, the firstnetwork device may determine to share the communication resources withthe second network device if the interference associated with the secondnetwork device exceeds both the lower and the upper interferencethresholds. In another embodiment, if reducing the transmit power willcause performance degradation in the first communication network or thesecond communication network, the first network device may determine toshare communication resources with the second network device.

In some embodiments, the first network device and the second networkdevice may exchange coexistence messages to divide the transmission timeinto multiple communication time slots. In this embodiment, each networkdevice may be allocated communication time slots for exclusive use bythe network device. For example, the PLC device may transmit and receivecommunications during the communication time slots allocated to the PLCdevice. The VDSL device may transmit and receive communications duringthe communication time slots allocated to the VDSL device. The PLCdevice may not transmit or receive communications during thecommunication time slots allocated to the VDSL device. Likewise, theVDSL device may not transmit or receive communications during thecommunication time slots allocated to the PLC device. In anotherembodiment, the first network device and the second network device mayexchange coexistence messages to divide a communication frequency bandinto multiple frequency sub-bands. In this embodiment, each networkdevice may be allocated one or more frequency sub-bands for exclusiveuse by the network device. For example, the PLC device may transmit andreceive communications on the frequency sub-bands allocated to the PLCdevice. The VDSL device may transmit and receive communications on thefrequency sub-bands allocated to the VDSL device. The PLC device may nottransmit or receive communications on the frequency sub-bands allocatedto the VDSL device. Likewise, the VDSL device may not transmit orreceive communications on the frequency sub-bands allocated to the PLCdevice. From block 414, the flow ends.

In some embodiments, after reducing the transmit power or sharing thecommunication resources, the first network device and the second networkdevice may continue to exchange coexistence messages and monitor theinterference. For example, after reducing the transmit power or sharingthe communication resources, the PLC device may continue to monitor theinterference associated with the VDSL device. The PLC device may notifythe VDSL device of the detected interference and receive updatesregarding the interference detected by the VDSL device. The PLC deviceand the VDSL device may communicate with each other to determine whetherto further reduce, increase, or maintain their respective transmitpower. In one example, the PLC device may notify the VDSL device toincrease its transmit power if the PLC device does not detect anyinterference from the VDSL network, if the PLC device will not beexchanging any messages in the PLC network, or if the PLC device willoperate in a low-power mode. As another example, the VDSL device maynotify the PLC device to increase its transmit power if the VDSL devicedoes not detect any interference from the PLC network, if the VDSLdevice will not be exchanging any messages in the VDSL network, or ifthe VDSL device will operate in a low-power mode. The PLC device and theVDSL device may communicate with each other to determine whether totransmit at a maximum transmit power and share communication resourcesinstead. For example, after reducing the transmit power to minimizeinterference with the VDSL network, the PLC device may detect aperformance degradation in the PLC network. Accordingly, the PLC devicemay transmit coexistence message to the VDSL device indicating that thePLC device will increase its transmit power (e.g., to the maximumtransmit power). The PLC device may also request the VDSL device toexchange coexistence messages to determine how to share communicationresources.

In FIGS. 3-4, the first network device and the second network devicecoordinate with each other to determine whether and how to reduce mutualinterference. However, in other embodiments, the first network deviceand/or the second network device may independently attempt to reduce theinterference generated at the other network device. In the symmetricinterference reduction technique described in FIG. 5, both the firstnetwork device and the second network device may share theresponsibility for reducing their respective transmit power. Forexample, if there is interference between a PLC device and a VDSLdevice, the PLC device and the VDSL device may independently reducetheir respective transmit power to minimize mutual interference withoutany input or collaboration between the network devices. In theasymmetric interference reduction technique described in FIG. 6, eitherthe PLC device or the VDSL device may reduce the transmit power tominimize interference to the other network device. In one embodiment,the network device associated with a lower priority may executeoperations to reduce the transmit power. The network device associatedwith the higher priority may not reduce its transmit power.

FIG. 5 is a flow diagram 500 illustrating example operations of asymmetric technique for minimizing interference between communicationnetworks. The flow 500 begins at blocks 502A and 502B. In the symmetrictechnique, a first network device of a first communication network and asecond network device of a second communication network independentlyexecute operations to determine by how much to reduce their respectivetransmit power. Blocks 502A-508A are executed by the first networkdevice to determine by how much to reduce the transmit power of thefirst network device. Blocks 502B-508B are independently executed by thesecond network device to determine by how much to reduce the transmitpower of the second network device.

At block 502A, the first network device of the first communicationnetwork determines an interference associated with the second networkdevice of the second communication network. For example, theinterference detection module 104 may determine the interferencegenerated by the network device 112 at the network device 102. In someembodiments, the first network device may detect the preamble of atransmission initiated by the second network device. The first networkdevice may then estimate the interference generated by the secondnetwork device based, at least in part, on the signal strength of thedetected preamble. In some embodiments, the first network device mayinclude preamble detection functionality. For example, the interferencedetection module 104 may be configured to detect the preamble oftransmissions generated by the second network device. In someembodiments, the first network device may be a PLC device and the secondnetwork device may be a VDSL device. In one example, the interferencedetection module 104 that is used to detect a PLC preamble may also beconfigured to detect a VDSL preamble. The first network device maydetermine the signal strength of the detected preamble of the secondnetwork device relative to the power detection threshold (or detectionsensitivity) of the first network device. The power detection thresholdof the first network device may refer to the minimum received signalstrength that can be detected by the first network device. For example,if the power detection threshold of the first network device is −50 dBand the signal strength of the received preamble is −20 dB, theinterference may be calculated as a difference of the signal strengthand the detection sensitivity (e.g., −30 dB).

Likewise, at block 502B, the second network device determines aninterference associated with the first network device. For example, theinterference detection module 114 may determine the interferencegenerated by the network device 102 at the network device 112. Forexample, the VDSL device may detect the preamble of a transmissioninitiated by the PLC device. The VDSL device may execute similaroperations described above to determine the interference associated withthe second network device based, at least in part on the signal strengthof the preamble of the PLC device. From block 502A, the flow continuesat block 504A. From block 502B, the flow continues at block 504B.

At block 504A, the first network device determines whether theinterference associated with the second network device exceeds aninterference threshold. The interference threshold may represent themaximum amount of interference that can be tolerated at the firstnetwork device. Likewise, at block 504B, the second network device maydetermine whether the interference associated with the first networkdevice exceeds an interference threshold. In some embodiments, theinterference threshold that is used by the first network device may bedifferent from the interference threshold that is used by the secondnetwork device. The first network device and the second network devicemay independently compare the detected interference against anappropriate interference threshold to determine whether to reduce thetransmit power. From block 504A, if the interference associated with thesecond network device exceeds the interference threshold, the flowcontinues at block 506A. Otherwise, the flow loops back to block 502Awhere the first network device continues to monitor the interferenceassociated with the second network device. Likewise, from block 504B, ifthe interference exceeds the interference threshold, the flow continuesat block 506B. Otherwise, the flow loops back to block 502B where thesecond network device continues to monitor the interference associatedwith the first network device.

At block 506A, the first network device determines a transmit powerreduction factor to reduce the transmit power of the first networkdevice based, at least in part, on the interference associated with thesecond network device. For example, the transmit power estimation module106 may determine the transmit power reduction factor for the networkdevice 102. The first network device may assume a reciprocalcommunication channel between the first network device and the secondnetwork device. In other words, the first network device may determinethat the second network device detects the same amount of interferencefrom the first network device as was detected by the first networkdevice from the second network device. For example, if the first networkdevice detects a −15 dB interference from the second network device, thefirst network device may assume that the second network device alsodetects a −15 dB interference from the first network device. In someembodiments, the transmit power reduction factor for the first networkdevice may be a function of (e.g., proportional to) the interferenceassociated with the second network device. For example, the transmitpower reduction factor for the first network device may be half theamount of the interference associated with the second network device. Inthis example, if the PLC device detects an interference of −15 dB, thePLC may device may assume that the VDSL device may also detect aninterference of −15 dB. The PLC device may determine to reduce itstransmit power by −7.5 dB. In the symmetric interference reductiontechnique, the VDSL device may also reduce its transmit power by −7.5dB, resulting in an overall transmit power reduction of −15 dB andeffectively zero interference. As another example, the transmit powerreduction factor for the first network device may be any suitablepercentage of the amount of the interference associated with the secondnetwork device. In another embodiment, the first network device mayreduce its transmit power to eliminate interference at the secondnetwork device (e.g., so that the first network device generates zerointerference at the second network device). In another embodiment, thefirst network device may determine to reduce its transmit power by apredefined transmit power reduction factor irrespective of theinterference associated with the second network device. In anotherembodiment, the first network device may determine to reduce itstransmit power by a different predefined transmit power reduction factordepending on the range in which the interference lies. For example, ifthe interference associated with the second network device falls withina first interference range, the first network device may select a firstpredefined transmit power reduction factor. If the interference fallswithin a second interference range, the first network device may selecta second predefined transmit power reduction factor, and so on. Inanother embodiment, the first network device may have a priori knowledgeof the minimum power that can be detected (“power detection threshold”or “detection sensitivity”) by the second network device. The firstnetwork device may select the transmit power reduction factor so thatthe interference generated by the first network device at the secondnetwork device is below the power detection threshold of the secondnetwork device. In one example, the first network device may select thetransmit power reduction factor so that the interference associated withthe second network device is below the power detection threshold of thesecond network device. As another example, the first network device mayselect the transmit power reduction factor so that the transmit power ofthe first network device is below the power detection threshold of thesecond network device. In another embodiment, the first network devicemay reduce its transmit power so that the interference detected at thesecond network device is below an interference threshold implemented bythe second network device. In one example, the first network device mayselect the transmit power reduction factor so that the interferenceassociated with the second network device is below the interferencethreshold of the second network device. As another example, the firstnetwork device may select the transmit power reduction factor so thatthe transmit power of the first network device is below the interferencethreshold of the second network device.

Likewise, at block 506B, the second network device determines thetransmit power reduction factor for reducing the transmit power of thesecond network device based, at least in part, on the interferenceassociated with the first network device. For example, the transmitpower estimation module 116 may use similar techniques described aboveto determine the transmit power reduction factor for the network device112. In some embodiments, the first network device and the secondnetwork device may use the same technique to estimate their respectivetransmit power reduction factor. However, in other embodiments, thefirst network device and the second network device may use differenttechniques to estimate their respective transmit power reduction factor.The first network device and the second network device may determinetheir respective transmit power reduction factors independent of eachother (e.g., without any communication or exchange of coexistenceinformation). From block 506A, the flow continues at block 508A. Fromblock 506B, the flow continues at block 508B.

At block 508A, the first network device reduces its transmit power bythe transmit power reduction factor. The first network device maytransmit subsequent messages in the first communication network at thereduced transmit power. Likewise, at block 508B, the second networkdevice reduces its transmit power by the transmit power reductionfactor. The second network device may transmit subsequent messages inthe second communication network at the reduced transmit power. In someembodiments, the first network device and the second network device mayindependently determine the same transmit power reduction factor forreducing their respective transmit power. In another embodiment, thefirst network device may reduce its transmit power by a first transmitpower reduction factor and the second network device may reduce itstransmit power by a second transmit power reduction factor that isdifferent from the first transmit power reduction factor. From block508A, the flow loops back to block 502A where the first network devicecontinues to monitor the interference associated with the second networkdevice. From block 508B, the flow loops back to block 502B where thesecond network device continues to monitor the interference associatedwith the first network device.

The first network device (e.g., PLC device) and the second networkdevice (e.g., VDSL device) can continue to independently monitor theinterference attributable to the other network device. The PLC devicemay reduce its transmit power until it cannot detect transmissions fromthe VDSL device. When the PLC device cannot detect transmissions of theVDSL device, the PLC device may assume that its transmit power issufficiently low so that the VDSL device cannot detect transmissions ofthe PLC device or the interference of the PLC device is below adetection threshold of the VDSL device. Likewise, the VDSL device mayreduce its transmit power until it cannot detect transmissions from thePLC device.

FIG. 6 is a flow diagram 600 illustrating example operations of anasymmetric technique for minimizing interference between communicationnetworks. The flow begins at block 602.

At block 602, a first network device of a first communication networkdetermines that the priority of the first network device is lower thanthe priority of a second network device of a second communicationnetwork. For example, the interference detection module 104 maydetermine that the network device 102 has a lower priority as comparedto the network device 112. In one embodiment, transmissions of a PLCdevice of a PLC network may interfere with transmissions of a VDSLdevice of a proximate VDSL network. In the asymmetric interferencereduction technique, either the PLC device or the VDSL device may reducethe transmit power to minimize interference to the other network device.For example, if the priority of the PLC device is lower than thepriority of the VDSL device, the PLC device may reduce its transmitpower to minimize interference detected by the VDSL device as will befurther described below. The flow continues at block 604.

At block 604, the first network device determines the interferenceassociated with the second network device. For example, the interferencedetection module 104 may determine the interference generated by thenetwork device 112 at the network device 102. In one embodiment, thefirst network device may use a preamble detection technique to detecttransmissions of the second network device for estimating theinterference associated with the second network device as describedabove in FIG. 5. For example, the first network device may detect thepreamble of transmissions initiated by the second network device. Thefirst network device may use the signal strength of the detectedpreamble to estimate the interference associated with the second networkdevice.

In another embodiment, the first network device may determine the signalstrength of transmissions from the second network device withoutexplicitly detecting the preamble of the second network device. Thefirst network device may notify other network devices within the firstcommunication network to defer transmissions during a predefined timeinterval. In doing so, the first network device may ensure that all thetransmissions detected at the first network device are attributable tothe second communication network. The first network device may estimatethe attenuation from the second network device to the first networkdevice based on knowledge of the transmit power of the second networkdevice and the signal strength of the detected transmission. In someembodiments, the first network device may also take the background noiseinto consideration to determine the attenuation from the second networkdevice to the first network device. For example, the PLC device maydetect VDSL transmissions and estimate the attenuation between the VDSLdevice and the PLC device. The PLC device may assume that the transmitpower of a VDSL transmission is constant at a known power spectraldensity (PSD). For example, the PLC device may detect a VDSLtransmission at −120 dB and may have a priori knowledge that the VDSLdevice has a transmit power of −60 dB. In this example, the PLC devicemay determine that the attenuation from the VDSL device to the PLCdevice is 60 dBm. The attenuation between the first network device andthe second network device may be representative of the interferenceassociated with the second network device and may be used to estimatethe transmit power reduction factor for the first network device as willbe described below. After determining the interference associated withthe second network device, the flow continues at block 606.

At block 606, the first network device determines whether theinterference associated with the second network device exceeds aninterference threshold. For example, the interference detection module104 may determine whether the interference associated with the secondnetwork device exceeds the interference threshold. In one embodiment,the interference threshold may be 0 dB (i.e., no interference). Inanother embodiment, the interference threshold may be approximatelyequal to the power detection threshold or detection sensitivity of thesecond network device. In another embodiment, the interference thresholdmay be determined based, at least in part, on the noise level in thefirst communication network, the receiver sensitivities of the othernetwork devices in the first communication network, performancerequirements associated with the first communication network, etc. Inanother embodiment, the interference detection module 104 may use theattenuation between the network devices 102 and 112 to determine whetheror not to reduce the transmit power of the network device 102. Forexample, if the attenuation between the first network device and thesecond network device exceeds an attenuation threshold, the firstnetwork device may determine not to reduce the transmit power of thefirst network device. If the attenuation does not exceed the attenuationthreshold, the first network device may determine to reduce the transmitpower of the first network device. If the interference associated withthe second network device does not exceed the interference threshold,the flow continues at block 608. However, if the interference associatedwith the second network device exceeds the interference threshold, theflow continues at block 610.

At block 608, the first network device determines not to reduce thetransmit power. If the interference generated by the second networkdevice at the first network device does not exceed the interferencethreshold, then assuming channel reciprocity, the first network devicedetermines that the interference generated by the first network devicewill not exceed the interference threshold at the second network device.From block 608, the flow loops back to block 604 where the first networkdevice continues to monitor the interference generated by the secondnetwork device.

At block 610, the first network device determines a transmit powerreduction factor to reduce the transmit power of the first networkdevice based, at least in part, on the interference of the secondnetwork device. For example, the transmit power estimation module 106may determine the transmit power reduction factor. The first networkdevice may assume a reciprocal channel and determine that the secondnetwork device detects the same amount of interference (and attenuation)from the first network device as was detected by the first networkdevice at block 604. Consequently, by reducing the transmit power at thefirst network device, the first network device may attempt to minimizethe interference detected at the second network device. Referring to theabove example, the first network device may determine a 60 dBattenuation from the second network device. To estimate the transmitpower reduction factor, the first network device may assume thatattenuation is symmetric and that the channel between the first and thesecond network devices is reciprocal. Accordingly, the first networkdevice may determine that transmissions from the first network deviceare attenuated by 60 dB before being received by the first networkdevice. The first network device may estimate a target transmit powerbased, at least in part, on the attenuation and knowledge of the powerdetection threshold of the second network device. The target transmitpower may represent the maximum transmit power at which the firstnetwork device can initiate transmissions in the first communicationnetwork without causing interference at the second network device. Inthis example, the first network device may a priori knowledge that thesecond network device can detect a minimum power of −140 dB. Based on anattenuation of −60 dB and a power detection threshold of the secondnetwork device of −140 dB, the first network device may determine thetarget transmit power as −80 dB. In some embodiments, the transmit powerreduction factor for the first network device may be determined from thetarget transmit power. For example, if the target transmit power is −80dB and the current transmit power is −50 dB, the first network devicemay select a transmit power reduction factor of −30 dB. In anotherembodiment, the first network device may determine to reduce itstransmit power by a predefined transmit power reduction factorirrespective of the attenuation and the target transmit power.

However, in some embodiments, the first network device may use theinterference generated by the second network device to estimate thetransmit power reduction factor. In some embodiments, the transmit powerreduction factor for the first network device may be a function of(e.g., proportional to) the amount of interference generated by thesecond network device. For example, if the first network device detectsa −15 dB interference from the second network device, the first networkdevice may assume that the second network device also detects a −15 dBinterference from the first network device. Because the second networkdevice does not reduce its transmit power in the asymmetric interferencereduction technique, the first network device may select a transmitpower reduction factor of 15 dB. In another embodiment, the transmitpower reduction factor for the first network device may be a suitablepercentage of the amount of the interference associated with the secondnetwork device. In another embodiment, the first network device mayreduce its transmit power to eliminate interference at the secondnetwork device (e.g., so that the first network device generates zerointerference at the second network device). In another embodiment, thefirst network device may determine to reduce its transmit power by apredefined transmit power reduction factor irrespective of theinterference associated with the second network device. In anotherembodiment, the first network device may determine to reduce itstransmit power by a different predefined transmit power reduction factordepending on the range in which the interference lies. For example, ifthe interference associated with the second network device falls withina first interference range, the first network device may select a firstpredefined transmit power reduction factor. If the interferenceassociated with the second network device falls within a secondinterference range, the first network device may select a secondpredefined transmit power reduction factor, and so on. In anotherembodiment, the first network device may select the transmit powerreduction factor so that the interference generated by the first networkdevice at the second network device is below the power detectionthreshold of the second network device. In another embodiment, the firstnetwork device may reduce its transmit power so that the interferencedetected at the second network device is below an interference thresholdimplemented by the second network device. The flow continues at block612.

At block 612, the first network device reduces its transmit power by thetransmit power reduction factor. The first network device can transmitsubsequent messages at the reduced transmit power. From block 612, theflow loops back to block 604 where the first network device continues tomonitor the interference associated with the second network device.

Although FIG. 6 describes operations for using the priority to determinewhich network device should reduce its transmit power, embodiments arenot so limited. In other embodiments, other suitable factors may be usedto determine which network device should execute the asymmetricinterference reduction technique and reduce its transmit power. Forexample, the network device with less stringent quality of servicespecifications may reduce its transmit power.

It should be understood that FIGS. 1-6 are examples meant to aid inunderstanding embodiments and should not be used to limit embodiments orlimit scope of the claims. Embodiments may comprise additional circuitcomponents, different circuit components, and/or may perform additionaloperations, fewer operations, operations in a different order,operations in parallel, and some operations differently. Althoughexamples describe the first network device using a preamble detectiontechnique to detect transmissions of the second network device forestimating interference using the symmetric interference reductiontechnique and the coordinated interference reduction technique,embodiments are not so limited. In other embodiments, the first networkdevice may use of a first communication network may estimate theinterference associated with the second network device of the secondcommunication network based, at least in part, on an attenuation betweenthe first network device and the second network device as describedabove in FIG. 6. For example, the first network device may cause othernetwork devices in the first communication network to temporarilydisable transmissions during a predefined time interval. Anytransmissions detected at the first network device during the predefinedtime interval may be attributed to the second network device (and thesecond communication network). The first network device may estimate theattenuation from the second network device to the first network devicebased, at least in part, on the signal strength of the transmissionsdetected during the predefined time interval. Assuming attenuationsymmetry and based on knowledge of the minimum power that can bedetected by the second device, the first network device can determinethe transmit power reduction factor so that the first network devicedoes not generate interference at the second network. In otherembodiments, the first network device and the second network device mayuse other suitable techniques to estimate the interference associatedwith the proximate communication network.

As described above in the asymmetric interference reduction technique,the first network device (e.g., the PLC device) may reduce its transmitpower so that the second network device (e.g., the VDSL device) does notdetect the transmissions of the first network device. However, thesecond network device does not reduce its transmit power. In someembodiments, after reducing the transmit power, the first network devicemay continue to determine whether a transmission from the second networkdevice was detected. By continuing to monitor the communication channelfor the presence of transmissions/interference from the second networkdevice, the first network device can vary the transmit power to takechanging channel conditions, error in interference estimation,background noise, and other such factors into consideration. Iftransmissions from the second network device are detected, the firstnetwork device can estimate the interference associated with thedetected transmission. The first network device may attempt to furtherreduce its transmit power to minimize interference at the second networkdevice. However, if transmissions from the second network device are notdetected, the first network device may determine that there is nointerference from the second network device, that the interference isbelow a detection threshold of the first network device, or that thesecond network device is no longer active. Assuming a reciprocalchannel, the first network device may determine that transmissions ofthe first network device will not be detected at the second networkdevice and will not affect the performance of the second network device.Consequently, the first network device may determine to increase itstransmit power. In some embodiments, the first network device mayincrease its transmit power to the maximum allowable transmit power andmay transmit subsequent messages using the maximum allowable transmitpower. However, in other embodiments, the first network device mayincrease the transmit power by a predefined power increment and maytransmit subsequent messages at the increased transmit power (that maynot be the maximum allowable transmit power).

Although embodiments describe the network devices 102 and 112 exchangingcoexistence messages to determine whether to share resources or reducethe transmit power, in other embodiments, the network devices 102 and112 may exchange coexistence messages to both reduce the transmit powerand share resources. For example, the network devices 102 and 112 mayreduce their respective transmit power in response to determining thatthe interference exceeds an interference threshold. The network devices102 and 112 may exchange coexistence messages to determine whether oneor both of the devices should reduce their respective transmit power, byhow much the network devices should reduce their respective transmitpower, etc. If the interference detected by one or both of the networkdevices continues to exceed the interference threshold even afterreducing the transmit power, the network devices 102 and 112 mayexchange coexistence messages to determine how to share communicationresources.

In some embodiments, operations for reducing the transmit power of thefirst network device in response to detecting the interference generatedby a second network device may be executed periodically to take intoconsideration variations in communication channel conditions, relocationof the first network device and/or second network device, addition ofnew devices to the first communication network and/or the secondcommunication network, etc.

In some embodiments, the first communication network and the secondcommunication network may include multiple network devices. However,each network device may detect a different amount of interference fromthe proximate communication network. For example, a first PLC device ofthe PLC network may detect interference from the VDSL network. However,a second PLC device of the PLC network may not detect any interferencefrom the VDSL network. In this example, the first PLC device may executesuitable operations described above to minimize the interference.However, the second PLC device may not execute the operations describedabove and instead, may continue to transmit at a maximum transmit power.

Although examples describe the first network device of the firstcommunication network detecting interference from a second networkdevice of the second communication network, embodiments are not solimited. In other embodiments, the first network device may detectinterference from multiple network devices of the second communicationnetwork. In this embodiment, the first network device may estimate thetransmit power reduction factor based on the strongest interferencegenerated by the second communication network. For example, a PLC devicemay detect interference from a first VDSL device and a second VDSLdevice. If the PLC device detects a higher amount of interference fromthe second VDSL device, the PLC device may determine the transmit powerreduction factor based on the interference generated by the second VDSLdevice.

As will be appreciated by one skilled in the art, aspects of thisdisclosure may be embodied as a system, method, or computer programproduct. Accordingly, aspects of this disclosure may take the form of anentirely hardware embodiment, a software embodiment (including firmware,resident software, micro-code, etc.) or an embodiment combining softwareand hardware aspects that may all generally be referred to herein as a“circuit,” “module,” “unit” or “system.” Furthermore, aspects of thisdisclosure may take the form of a computer program product embodied inone or more computer readable medium(s) having computer readable programcode embodied thereon.

Any combination of one or more non-transitory computer readablemedium(s) may be utilized. Non-transitory computer-readable mediacomprise all computer-readable media, with the sole exception being atransitory, propagating signal. The non-transitory computer readablemedium may be a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

Computer program code embodied on a computer readable medium forcarrying out operations for aspects of this disclosure may be written inany combination of one or more programming languages, including anobject oriented programming language such as Java, Smalltalk, C++ or thelike and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of this disclosure are described with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of this disclosure.It will be understood that each block of the flowchart illustrationsand/or block diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

FIG. 7 is a block diagram of one embodiment of an electronic device 700including a mechanism for minimizing interference between communicationnetworks. In some embodiments, the electronic device 700 may be adedicated PLC device, a dedicated VDSL device, a desktop computer, alaptop computer, a tablet computer, a smart appliance, a televisionset-top box, a gaming console, or other electronic device that includeshardware, software, and/or firmware to implement PLC protocols or VDSLprotocols for communication. The electronic device 700 includes aprocessor 702 (possibly including multiple processors, multiple cores,multiple nodes, and/or implementing multi-threading, etc.). Theelectronic device 700 includes a memory 706. The memory 706 may besystem memory (e.g., one or more of cache, SRAM, DRAM, zero capacitorRAM, Twin Transistor RAM, eDRAM, EDO RAM, DDR RAM, EEPROM, NRAM, RRAM,SONOS, PRAM, etc.) or any one or more of the above already describedpossible realizations of computer-readable storage media. The electronicdevice 700 also includes a bus 710 (e.g., PCI, ISA, PCI-Express,HyperTransport®, InfiniBand®, NuBus, AHB, AXI, etc.), and networkinterfaces 704 that include at least one of a wireless network interface(e.g., a WLAN interface, a Bluetooth® interface, a WiMAX interface, aZigBee® interface, a Wireless USB interface, etc.) and a wired networkinterface (e.g., a PLC interface, a DSL interface, an Ethernetinterface, etc.).

The electronic device 700 also includes a communication module 708. Thecommunication module 708 includes an interference detection module 712and a transmit power estimation module 714. A coexistence module 716 inthe communication module 708 is depicted using dashed lines to indicatethat it is optional; i.e., the electronic device 700 may or may notinclude the coexistence module 716 (e.g., coexistence functionality)depending on the implementation. The communication module 708 mayattempt to minimize interference between the electronic device 700(“first electronic device”) of a first communication network and asecond electronic device of a proximate second communication network. Inone embodiment, the communication module 708 of the first electronicdevice may exchange coexistence messages with the second electronicdevice to determine whether to reduce the transmit power or sharecommunication resources, as described in FIGS. 1-4. In anotherembodiment, the communication module 708 may determine by how much toreduce the transmit power of the first electronic device based, at leastin part, on the interference associated with the second electronicdevice, as described in FIGS. 1 and 5. In this embodiment, the firstelectronic device and the second electronic device may independentlyreduce their respective transmit power based, at least in part, on theinterference associated with the other electronic device withoutcoordination between the two electronic devices. In another embodiment,the communication module 708 may determine to reduce the transmit powerof the first electronic device if the priority of the first electronicdevice is lower than priority of the second electronic device, asdescribed in FIGS. 1 and 6. However, the communication module 708 maynot reduce the transmit power of the first electronic device if thepriority of the first electronic device exceeds the priority of thesecond electronic device. Instead, the first electronic device may relyon the second network device to reduce the transmit power of the secondnetwork device.

Any one of these functionalities may be partially (or entirely)implemented in hardware and/or on the processor 702. For example, thefunctionality may be implemented with a system-on-a-chip (SoC), anapplication specific integrated circuit (ASIC), in logic implemented inthe processor 702, in a co-processor on a peripheral device or card,etc. Further, realizations may include fewer or additional componentsnot illustrated in FIG. 7 (e.g., video cards, audio cards, additionalnetwork interfaces, peripheral devices, etc.). For example, in additionto the processor 702 coupled with the bus 710, the communication module708 may comprise at least one additional processor module. As anotherexample, the communication module 708 may include one or more radiotransceivers, processors, memory, and other logic to implement thecommunication protocols and related functionality. The processor 702,the memory 706, and the network interfaces 704 are coupled to the bus710. Although illustrated as being coupled to the bus 710, the memory706 may be coupled to the processor 702. For example, in addition to theprocessor 702 coupled with the bus 710, the electronic device 700 maycomprise at least one additional processor module.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of this disclosure isnot limited to them. In general, techniques for minimizing interferencebetween communication networks as described herein may be implementedwith facilities consistent with any hardware system or hardware systems.Many variations, modifications, additions, and improvements arepossible.

Plural instances may be provided for components, operations, orstructures described herein as a single instance. Finally, boundariesbetween various components, operations, and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of this disclosure. Ingeneral, structures and functionality presented as separate componentsin the exemplary configurations may be implemented as a combinedstructure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements may fall within the scope of this disclosure.

What is claimed is:
 1. A method for minimizing communicationinterference comprising: determining, by a first network device of afirst communication network, an interference level associated with asecond network device of a second communication network; determining, inresponse to determining that the interference level does not exceed aninterference threshold, to reduce at least one member selected from thegroup consisting of: a first transmit power of the first network device,and a second transmit power of the second network device; anddetermining to share a communication resource between the first networkdevice and the second network device in response to determining that theinterference level exceeds the interference threshold.
 2. The method ofclaim 1, further comprising: determining to transmit a coexistencemessage from the first network device to the second network device,wherein determining to share the communication resource is based, atleast in part, on the coexistence message.
 3. The method of claim 2,wherein the coexistence message is transmitted via a third network. 4.The method of claim 2, wherein determining to share the communicationresource comprises at least one member selected from the groupconsisting of: sharing the communication resource in a time domain; andsharing the communication resource in a frequency domain.
 5. The methodof claim 1, further comprising: determining a first transmit powerreduction factor in response to determining to reduce the first transmitpower, the second transmit power, or a combination thereof; determiningto transmit a coexistence message comprising the transmit reductionfactor from the first network device to the second network device toreduce the second transmit power by the first transmit power reductionfactor.
 6. The method of claim 5, wherein the first transmit powerreduction factor is determined based, at least in part on a priority ofthe first network device.
 7. The method of claim 5, further comprising:determining a performance degradation in the second communicationnetwork based, at least in part, on determining to reduce the secondtransmit power by the first transmit power reduction factor; anddetermining to share the communication resource between the firstnetwork device and the second network device in response to determiningthe performance degradation.
 8. The method of claim 5, furthercomprising: determining a second transmit power reduction factor; anddetermining to reduce the first transmit power by the second transmitpower reduction factor.
 9. The method of claim 8, further comprising:determining a performance degradation in the first communication networkbased, at least in part, on determining to reduce the first transmitpower by the second transmit power reduction factor; and determining toshare the communication resource between the first network device andthe second network device in response to determining the performancedegradation.
 10. The method of claim 8, wherein the first transmit powerreduction factor and the second transmit power reduction factor aredetermined based, at least in part, on the interference level.
 11. Themethod of claim 1, wherein determining the interference level comprises:determining a signal strength of a preamble of a transmission receivedfrom the second network device; and determining the interference levelbased, at least in part, on a difference between the signal strength anda power detection threshold associated with the first network device,wherein the power detection threshold is a minimum signal strength thatcan be received by the first network device.
 12. The method of claim 1,wherein determining the interference level comprises: providing acoexistence message to the second network device via a thirdcommunication network to select a time interval for determining theinterference level; detecting a transmission of the second networkdevice during the time interval; and determining the interference levelbased, at least in part, on the transmission.
 13. The method of claim12, further comprising: notifying other network devices of the firstcommunication network to defer transmissions during the time interval.14. The method of claim 1, wherein, the first network device and thefirst communication network implement one or more powerlinecommunication (PLC) protocols; and the second network device and thesecond communication network implement one or more digital subscriberline (DSL) protocols.
 15. A first network device of a firstcommunication network, the first network device comprising: a processor;and a memory to store instructions, the instructions when executed bythe processor, cause the first network device to: determine aninterference level associated with a second network device of a secondcommunication network; determine, in response to determining that theinterference level does not exceed an interference threshold, to reduceat least one member selected from the group consisting of: a firsttransmit power of the first network device, and a second transmit powerof the second network device; and determine to share a communicationresource between the first network device and the second network devicein response to determining that the interference level exceeds theinterference threshold.
 16. The first network device of claim 15,wherein the instructions further cause the first network device to:determine to transmit a coexistence message from the first networkdevice to the second network device, wherein determining to share thecommunication resource is based, at least in part, on the coexistencemessage.
 17. The first network device of claim 16, wherein theinstructions that cause the first network device to determine to sharethe communication resource comprise at least one member selected fromthe group consisting of: instructions that cause the first networkdevice to share the communication resource in a time domain; andinstructions that cause the first network device to share thecommunication resource in a frequency domain.
 18. The first networkdevice of claim 15, wherein the instructions further cause the firstnetwork device to: determine a first transmit power reduction factor inresponse to determining to reduce the first transmit power, the secondtransmit power, or a combination thereof; determine to transmit acoexistence message comprising the transmit reduction factor from thefirst network device to the second network device to reduce the secondtransmit power by the first transmit power reduction factor.
 19. Thefirst network device of claim 18, wherein the instructions further causethe first network device to: determining a second transmit powerreduction factor; and determining to reduce the first transmit power bythe second transmit power reduction factor.
 20. The first network deviceof claim 19, wherein the first transmit power reduction factor and thesecond transmit power reduction are determined based, at least in part,on the interference level.
 21. A non-transitory machine-readable storagemedium having machine executable instructions stored therein, themachine executable instructions comprising instructions to: determine aninterference level associated with a second network device of a secondcommunication network; determine, in response to determining that theinterference level does not exceed an interference threshold, to reduceat least one member selected from the group consisting of: a firsttransmit power of a first network device, and a second transmit power ofthe second network device; and determine to share a communicationresource between the first network device and the second network devicein response to determining that the interference level exceeds theinterference threshold.
 22. The non-transitory machine-readable storagemedium of claim 21, further comprising instructions to: determine totransmit a coexistence message from the first network device to thesecond network device, wherein determining to share the communicationresource is based, at least in part, on the coexistence message.
 23. Thenon-transitory machine-readable storage medium of claim 22, wherein theinstructions that cause the first network device to determine to sharethe communication resource comprise at least one member selected fromthe group consisting of: instructions that cause the first networkdevice to share the communication resource in a time domain; andinstructions that cause the first network device to share thecommunication resource in a frequency domain.
 24. The non-transitorymachine-readable storage medium of claim 21, further comprisinginstructions to: determine a first transmit power reduction factor inresponse to determining to reduce the first transmit power, the secondtransmit power, or a combination thereof; determine to transmit acoexistence message comprising the transmit reduction factor from thefirst network device to the second network device to reduce the secondtransmit power by the first transmit power reduction factor.
 25. Thenon-transitory machine-readable storage medium of claim 24, furthercomprising instructions to: determining a second transmit powerreduction factor; and determining to reduce the first transmit power bythe second transmit power reduction factor.
 26. The non-transitorymachine-readable storage medium of claim 25, wherein the first transmitpower reduction factor and the second transmit power reduction factorare determined based, at least in part, on the interference level.